Pumps static discharge head

Static Discharge Head The static discharge head is the vertical distance measured from the free surface of the hquid in the receiver to the pump centerhne, plus the absolute pressure at the hquid surface. Total static head hf, is the difference between discharge and suction static heads. 

The total head on the pumps in Fig. 6.13d, c, and /is computed in the same way as described above, except that the total static head is less because the pump has a static suction head—that is, the elevation of the liquid on the suction side reduces the total distance through which the pump must discharge liquid thus the total static head is less. The static suction head is subtracted from the static discharge head to determine the total static head on the pump. 

The terms suction and discharge in the context of heads refer to portions of the system before and after the pumping station, respectively. Static suction lift h( is the vertical distance from the elevation of the inflow liquid level below the pump inlet to the elevation of the pump centerline or eye of the impeller. A lift is a negative head. Static suction head h, is the vertical distance from the elevation of the inflow liquid level above the pump inlet to the elevation of the pump centerline. Static discharge head h is the vertical distance from the centerline elevation of the pump... 

Static discharge head—The vertical distance from the pump centerline to the elevation of the discharge liquid level. 

Static Discharge Head. The vertical elevation from the center line of the pump to the point of free discharge. 

The discharge head of a pump is the head measured at the discharge nozzle (gauge or absolute), and is composed of the same basic factors previously summarized 1. static head 2. friction losses through pipe, fittings, contractions, expansions, entrances and exits 3. terminal system pressure. 

Hs0 = Head at no flow, or shutoff, ft I4ms = Head of viscous fluid, ft Hw = Water equivalent head, ft hd = Discharge head on a pump, ft of fluid hs = Suction head (or suction lift) on a pump, ft of fluid hSL, hDL = Friction losses in pipe and fittings , subscript SL for suction line and DL for discharge line, ft of fluid hv = Velocity head, ft of fluid L = S = Static head, suction side, ft (Figure 3-38)... 

Centrifugal pumps, 181 Discharge systems, 187 Example calculation, 186 Flow friction losses, 185. 186 Friction losses, pipe, see Chapter 2 Friction, 188 Pressure head, 184—186 Static head, 184-186 Suction head, 184, 185 Suction lift, 184, 185 Suction systems, 186 Hvdroclones, 265—267 Application system, 267 Ignition, flammable mixtures, 493 Impellers, centrifugal, reducing diameter, 203 Impellers,... 

Analyze a set of pump and system characteristic curves for the following conditions friction losses without static head, friction losses with static head, pump without lift, system with little friction and much static head, system with gravity head, system with different pipe sizes, system with two discharge heads, system with diverted flow, and effect of pump wear on characteristic curve. 

A variable speed pump can be a solution but the user needs to be aware of a dead band that is artificially introduced into the electronics and the minimum discharge head requirements to prevent reverse flow for varying static heads [Ref. 6.41,... 

One component of the TDH is the Hs, the static head. In this example the surface level in the discharge tank is 115.5 ft above the pump centerline. The surface level in the suction tank is 35.5 ft above the pump centerline. The AHs, by observation is 80 ft. See Figure 8-6. 

Discharge static head H (from centerline of pump) Suction static head S, (actually -HS)... 

Note that both the discharge and suction pressures must be on the same base/units. These illustrations are for static head only, while overall (he pump has to work against the static and the pressure heads. (To be discussed.)... 

It is important to recognize that a cenlrijugal pump will operate only along its performance curve [10, II]. External conditions will adjust themselves, or must be adjusted in order to obtain stable operation. Each pump operates within a system, and the conditions can be anticipated if each component part is properly examined. The system consists of the friction losses of the suction and the discharge piping plus the total static head from suction to final discharge point. Figure 3-51 represents a typical system head curve superimposed on the characteristic curve for a 10 by 8-inch pump with a 12-inch diameter impeller. 

In equation 4.3, hfd is the head loss due to friction, zd is the static head and Pd is the gas pressure above the liquid in the tank on the discharge side of the pump. 

A centrifugal pump is used to pump a liquid in steady turbulent flow through a smooth pipe from one tank to another. Develop an expression for the system total head A/t in terms of the static heads on the discharge and suction sides zd and zs respectively, the gas pressures above the tanks on the discharge and suction sides Pd and Ps respectively, the liquid density p, the liquid dynamic viscosity p, the gravitational acceleration g, the total equivalent lengths on... 

Specified discharge pressure shall be at the purchaser discharge connection. Hydraulic performance shall be corrected for column static and friction head losses. Bowl or pump casing performance curves shall be furnished with the correction indicated. 

The difference between the pump discharge pressure curve and the system curve (which is the sum of the static head and the pipe friction loss) is the available valve differential. 

A generalized equation, describing the system curve of a process is P = H + Ff(Qx), where P is the required to pump discharge pressure, H is the static or elevation head, Ff is the friction factor, Q is the flow rate, and x is an exponent that varies between 1.7 and 2.0 usually, 2.0 is used. 

Total 1 = Static Static head discharge L=I02 (30.6 m) Pump... 

Compute the total pumping head. The total head, expressed in feet of water, equals static head + friction head + required nozzle head = 10 + 35 + 8(0.434) = 48.5 ft of water (145.0 kPa). A pump having a total head of at least 50 ft of water (15.2 m) would be chosen for this spray pond. If future expansion of the pond is anticipated, compute the probable total head required at a future date and choose a pump to deliver that head. Until the pond is expanded, the pump would operate with a throttled discharge. Normal nozzle inlet pressures range from about 6 to 10 lb/in2 (41.4 to 69.0 kPa). Higher pressures should not be used, because there will be excessive spray loss and rapid wear of the nozzles. 

A centrifugal pump consists of a casing in which revolves an impeller, that is a wheel carrying a number of suitably shaped vanes. The centrifugal force sets up a static head in the casing and a certain velocity is imparted to the liquid. With the discharge valve closed only the static head is noticeable and can be... 

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